HIVST may be an important tool to reach underserved populations with PrEP.

• HIVST is an option to support PrEP delivery; its use should be driven by client needs and preferences. There is a range of PrEP options available for which HIVST use could be considered, including oral PrEP and the dapivirine vaginal ring (DVR). HIVST can also be considered as part of post-exposure prophylaxis (PEP) implementation. Further research is needed on the role of HIVST in the use of long-acting injectable prevention options, such as cabotegravir (CAB-LA). Self-testing refers to a process whereby people collect their own specimen using a simple rapid test and then perform the test and interpret their results when and where they want. WHO recommends a range of self-testing approaches which can improve access to and uptake of testing services, including those for pregnancy (40), HIV (11), HCV (41), syphilis and COVID-19 (42) (see for example, Figure 5.1). New dual self-tests, which can detect syphilis and HIV infection at the same time, are also recommended (43). See Box 5.8 for a summary of self-testing recommendations. Self-testing has been consistently shown to be safe, acceptable, and effective in increasing the number of people tested, diagnosed with and treated. While efforts to optimize linkage are important, studies have consistently shown that linkage rates following self-testing continue to be high and comparable to standard testing (44-46). The empowering nature of self-testing has also enabled people, including partners and people with limited contact with the health system, to access testing along with onward prevention, care and treatment services. Self-tests could be distributed through pharmacies, vending machines, pick-up from a local store, distribution by peers, community-based distribution, online ordering, mail delivery and facility-based distribution. Self-testing can enable greater flexibility for clients and health services, particularly as part of simplified implementation of PrEP and PEP services (3). A range of support tools can be utilized to support self-testing implementation (47), including virtual interventions and artificial intelligence (48). Evidence has shown that both blood-based and oral fluid-based self-tests are acceptable, and different users have different preferences (49-60). There is currently no evidence that there are differences in user uptake when offering either blood-based or oral fluid-based self-tests. There are currently a range of affordable WHO prequalified self-tests that can be accessed: https:// extranet.who.int/prequal/vitro-diagnostics/prequalification-reports/whopr.